| 摘要 |
A latch mechanism for a manhole cover in which a rotatable operator member has a threaded portion engaged with a threaded bore in a cam pin which rides in a pair of cam slots in a latching member to cause the latching member to be extended or retracted upon rotation of the operator member in either direction. The threads disengage when the latch member reaches a fully retracted position so that the operating member can freely spin thereafter in the same direction, while the threads reengage when the operator member is rotated in the opposite direction to begin movement of the latch member out of the housing.
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